The present invention relates to a method for filling seed trays and more particularly to a method for filling tobacco seed trays whereby dry pockets are prevented from forming in the seed trays.
Generally, tobacco plants are grown from seed and when the tobacco seedlings reach a specific height, they are transplanted to the tobacco field. The tobacco seedlings can be raised from seeds in trays which float on water in, for instance, a greenhouse or similar type structure. The trays are generally rectangular in shape and have rows of individual pockets formed therein. For instance, a conventional tobacco seed tray may comprise 12 rows of 24 pockets in each row. The individual pockets are filled with filler material (organic matter, peat, etc.) specially formulated to enhance germination and growth of seedlings from the tobacco seeds.
After the pockets are filled with the filler material, divots or holes are formed in the top of the filler material of each pocket by, for example, placing a templet over the seed tray. The templet has protrusions matching the number of pockets in the seed tray, the protrusions forming the divots in the filler material. Subsequently, seeds are placed in the divots of each pocket by, for example, an automatic seeding device, and the seed tray is then floated in water. At the bottom of each pocket there is usually a hole in the seed tray so that the filler material can wick water through the hole into the pocket.
A conventional method and apparatus for filling the seed trays with filler material includes loading a hopper with the filler material and passing the seed trays under the hopper whereby the filler material drops from the hopper into the seed trays.
A major drawback of the conventional method for loading the tobacco trays with the filler material is that air voids are formed at the bottom of a substantial number of individual pockets of each tray resulting in what is commonly referred to as "dry pockets." When a dry pocket is formed, water will not wick into that pocket and the tobacco seed will not germinate. The filler material must completely fill the pocket to draw the water through the hole in the bottom of the pocket. The air space in a dry pocket will prevent wicking from occurring.
It is generally impossible to tell if dry pockets have formed in the tobacco seed trays until the trays have been floating in water for a period of time. Normally, the filler material in a particular pocket will absorb water and turn a darker shape if the pocket is properly filled. The filler material in the dry pockets will not absorb water and thus, will not darken. The pocket can be poked with, for instance, a probe or rod to allow the air to escape and the filler material to settle and completely fill the pocket but, precious time has already been lost. Additionally, it is an extremely tedious and labor intensive process to correct every dry pocket that forms in the seed trays. In many instances, the farmer is forced to accept the dry pockets as waste and continue to raise the seedlings that have taken.
The conventional method of filling seed trays with a loading device, or hopper, allows for a great number of seed trays to be filled in a relatively short time period but, the formation of dry pockets is a major drawback. The hopper is generally filled with the filler material and maintained at full capacity during the filling process. The trays are pushed or otherwise conveyed, with a mechanical arm, for example, below the hopper while the filler material dumps into the trays so that all of the individual pockets in the tray are filled virtually simultaneously. The filler material tends to "bridge" across the pockets without filling the pocket completely. Air voids or spaces are formed in the pockets and, hence, dry pockets occur.
The present method for filling seed trays utilizes the advantages of a conventional hopper and mechanical vibrator and overcomes the noted disadvantages of the conventional devices by minimizing the occurrence or formation of dry pockets altogether.